Process for cooking woodchips with a liquor containing condensation product of vicinal epoxide and phenol



United States Patent Oflice 3,446,700 Patented May 27, 1969 3,446,700 PROCESS FOR COOKING WOODCHIPS WITH A LIQUOR CONTAINING CONDENSATION PROD- UCT OF VICINAL EPOXIDE AND PHENOL Daniel H. Hall, Essex Fells, N.J., assignor to Diamond Shamrock Corporation, a corporation of Delaware No Drawing. Filed Mar. 7, 1966, Ser. No. 532,068

Int. Cl. D21c 3/20 US. Cl. 162--72 Y 3 Claims ABSTRACT OF THE DISCLOSURE A process for the manufacture of pulp from wood chips employs a cooking liquor containing a treating agent obtained by condensing a vicinal epoxide having two to three carbon atoms with phenol or an alkyl phenol having from one to four carbon atoms in the alkyl radical.

This invention relates to the manufacture of wood pulp and more particularly to improved treating agents for use in the pulping of wood chips.

The manufacture of woodpulp is essentially achieved by the reduction of wood chips to the fibrous state. Reduction of wood chips to pulp is accomplished by removal of noncellulosic materials from the chips so that the resulting pulp is predominantly cellulose fibers. It is essential that most of the lignin binding the cellulose fibers in the wood chips be removed and that little if any degradation of the cellulose fibers occurs during pulping so that optimum yields of cellulose fibers of higher purity, quality, and strength are obtained. Since the properties of the resulting pulp determines the type and quality of products which can be made from the pulp, improvements in the manufacture of wood pulp are of great importance in that they result in pulps which have greater utility and find larger numbers of applications.

The pulping art has heretofore found limited application for nonionic surfactants in the treatment of wood pulp to facilitate the removal of resins from wood pulps. The nonionic surfactants which have been employed in wood pulp manufacture are the condensation products of ethylene oxide with octylphenol, nonylphenol, dioctylphenol, lauryl alcohol, tall oil, cashew nut shell oil, rosin and hydrogenated rosin and contain from 50% to 80% by weight of reacted ethylene oxide. Nonionic surfactants or nonionic surface active products or compounds which are hydrophilic-hydrophobic combinations. These surfactants contain a hydrophobic group of a hydrocarbon character together with a hydrophilic group which is composed of alkylene glycol ether radicals obtained by reacting vicinal epoxides such as ethylene oxide, propylene oxide, the like or their mixtures with an active hydrogen atom present in the hydrophobic group. The surfactants are interfacially active in that the hydrophobic group has an attraction for oil and other hydrophobic materials while the hydrophilic group has an attraction for water and other hydrophilic materials. Consequently, these combination or compounds tend to concentrate wherever there is an oil-water interface to lower the interfacial tension at the interface by positive adsorption therein. These compounds are interfacially active in that they reduce the interfacial tension at the interface. The term nonionic surfactants or nonionic surface active agent is used to describe the abovementioned water-soluble condensation products which will reduce interfacial tension. Anionic surfactants such as alkylaryl sulfonates and the like have also been used to a limited extent in wood pulp manufacture.

An object of the present invention is to provide an im proved process for the manufacture of wood pulp. Another object is to provide treating agents for use in the manufacture of wood pulp from wood chips. A further object is to provide an improved process for the manufacture of wood pulp which employs a new and novel class of Wood pulp treating agents. Still another object is to provide a new and novel class of wood pulp treating agents which produce pulps having lower permanganate numbers, lower resin contents and other improved properties. The new treating agents have the further advantage .in that they produce improved pulp yields and the resulting pulps have improved qualities which make them useful in a larger number of applications. A further object is to develop a new and novel class of treating agent for use in the manufacture of kraft pulp. Other objects will become apparent from the detailed description given hereinafter. It is intended, however, that the detailed description and specific examples do not limit the invention but merely indicate preferred embodiments thereof since various changes and modifications within the scope of the invention will become apparent to those skilled in the art.

The above as well as other objects have been most unexpectedly achieved in the following manner. I have found that addition of treating agents of the formula:

wherein R represents hydrogen or an alkyl group containing from one to four carbon atoms, R represents hydrogen or an alkyl group containing from one to four carbon atoms with the proviso that the sum of the carbon atoms in R and R does not exceed four carbon atoms, A represents the divalent residue of a vicinal epoxide containing from two to three carbon atoms and n represents an integer of from about 1 to 30, during the manufacture of wood pulp from wood chips results in improved yields of wood pulps having improved properties. It was completely unexpected that these treating agents which are not regarded in the art as having surface active properties and are not considered to be nonionic surfactants would be useful in improving the yields and properties of wood pulps obtained in the wood pulping process. I have found that use of these treating agents in the manufacture of wood pulp from wood chips results in higher yields of wood pulps having lower permanganate numbers, lower resin contents and other improved properties which make the pulps useful in a larger number of applications.

These treating agents are prepared by condensing vicinal epoxides containing from two to three carbon atoms with phenolic compounds such as phenol and alkylphenols containing from one to four carbon atoms in the alkyl radicals. Such condensation products are prepared by reacting from about 1 to about 30 moles of the vicinal expoxide with one mole of phenolic compound or compounds at temperatures from about C. to about C. in the presence of an alkali catalyst such as sodium methylate, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like with the preferred range of vicinal expoxide being from about 3 moles to about 20 moles per mole of phenolic compound. Vicinal expoxides which are particularly useful in the present invention include ethylene oxide, propylene oxide and mixtures of ethylene oxide and propylene oxide. If desired, the phenolic compounds can be first reacted with ethylene oxide and then with propylene oxide or vice versa to obtain variations in the hydrophilic group -(AO) H in the treating agent. For example, the phenolic compounds can be reacted with successive amounts of ethylene oxide and propylene oxide so be reacted with ethylene oxide and then capped with propylene oxide so that the hydrophilic group -(AO) H contains a plurality of ethylene glycol ether radicals and a single propylene glycol ether radical. As examples of phenolic compounds which can be employed in the preparation of these treating agents there may be mentioned phenol, cresols such as 2-methylphenol (o-cresol), 3- methylphenol (nr-cresol) and 4-methylphenol (p-cresol), 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, Z-n-propylphenol, 3-n-propylphenol, 4-n-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-n-butylphenol, 3-n-butylphenol, 4-n-butylphenol, 2-sec-butylphenol, 4-sec-butylphenol, 2-tert-butylphenol, 4-tert-butylphenol, xylenols such as 2,3-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,6-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, disubstituted phenols such as 2 methyl 4-ethylphenol, 2-methyl-4-isopropylphenol, 2,6-diethylphenol and the like. It is to be understood that mixtures containing two or more of the abovementioned phenolic compounds can also be employed.

The treating agents are normally added to the formulations of cooking chemicals employed in the production of Wood pulp from wood chips. The quantity of treating agents is present in effective amounts suflicient to achieve the desired results. Generally, they are present in amounts of from 0.5 pound to about pounds per ton of dry wood chips with the preferred range being from about 1 pound to about 7 pounds per ton of dry wood chips. Usually the treating agents are added to the solution of the cooking chemicals or liquor employed in the pulping process. If. a portion of the cooking chemicals containing the treating agents is recycled, sufiicient treating agent is added to the recycle solution to obtain the abovementioned concentrations. If desired, the treating agent may be added to the dry wood chip charge before charging or after charging into the digester and the cooking chemicals then added. It is to be understood that any other method or order of addition of the treating agents can be employed if desired. Since the composition of the solution of cooking chemicals can vary widely depending upon the type of pulping process employed, or whether the process is a chemical pulping process or a semichemical process, i.e., a process in which mechanical pulping is also used in conjunction with chemical pulping, the present invention can best be described by reference to use of the treating agents in specific pulping processes.

The following sets forth with more particularity the application of the present invention to the various pulping processes, i.e., kraft, soda and sulfite processes. These processes are carried out in the following manner. For sake of convenience, reference is made to a ton of dry wood chips as a basis for illustrating the proportions. For example, in the kraft process or in the kraft semichemical process a ton of dry wood chips is charged into the digester. Then from about 5000 pounds to about 13,000 pounds of a kraft cooking liquor containing from about 150 pounds to about 400 pounds of sodium hydroxide per ton of dry wood chips, from about 50 pounds to about 300 pounds of sodium sulfide per ton of dry wood chips, from about 25 pounds to about 200 pounds of sodium carbonate per ton of dry wood chips, from about 5000 pounds to about 12,000 pounds of water per ton of dry wood chips and from about 0.5 pound to about 10 pounds of the treating agent per ton of dry wood chips are charged to the digester. The alkalinity of the solution is from about to about by weight calculated at N21 O and the sul fidity is from about 20% to about by weight calculated as Na O. The ratio of liquor to chips in the cook may vary from about 3:1 to about 5:1. The charge in the digester is brought up to an operating temperature of from about 160 C. to about 180 C. and a pressure of from about 100 p.s.i.g. to about 125 p.s.i.g. The charge is held in this temperature and pressure range for from about 2 hours to about 5 hours to complete the pulping process.

The present invention can alsobe used in soda pulping processes and in semichemical soda pulping processes in which mechanical pulping is used to reduce the consumption of soda. Such processes are carried out in the following manner. A ton of dry wood chips is charged into the digester. In the soda process from about 4,000 pounds to about 11,000 pounds soda cooking liquor containing from about 300 pounds to about 800 pounds of sodium hydroxide per ton of dry wood chips, from about 40 pounds to about 150 pounds of sodium carbonate per ton of dry wood chips, from about 4,000 pounds to about 11,- 000 pounds of water per ton of dry wood chips and form about 0.5 pound to about 10 pounds of treating agent per ton ofdry wood chips are charged to the digester. The alkalinity of the solution is from about 18% to about 35% by weight calculated as NaOH. The ratio of liquor to chips in the cook may vary from about 3:1 to about 5:1. The charge in the digester is brought up to an operating temperature or from about 325 F. to about 350 F. and an operating pressure of from about p.s.i.g. to about 110 p.s.i.g. The charge is then held in this temperature and pressure range for about 2 hours to about 8 hours to complete the pulping process.

Likewise, the present invention can be used in sulfite pulping processes and semichemical sulfite pulping processes. These processes can be carried out in the following manner. A ton of dry wood chips is charged into the digester. Then from about 5,000 pounds to about 12,000 pounds of a sulfite cooking liquor containing from about 200 pounds to about 500 pounds of sulfurous acid per ton of dry wood chips, from about pounds to about 350 pounds calcium bisulfite per ton of dry wood chips, from about 5,000 pounds to about 11,000 pounds of water per ton of dry wood chips and from about 0.5 pound to about 10.0 pounds of the treating agent per ton of dry wood chips are charged to the digester. The ratio of liquor to chips in the cook may 'vary in practice from about 3:1 to about 6:1. The charge in the digester is brought up to an operating temperature of from about 325 F. to about 345 F. and an operating pressure of from about 90 p.s.i.g. to about p.s.i.g. The charge is held within this temperature and pressure range for from about 5 hours to about 8 hours to complete the pulping process.

It is of course to be understood that the present invention relates to cooking processes using the novel treating agents in the various kraft, soda and sulfide cooking liquors employed in pulp manufacture. These cooking liquors are well known in the art of pulp manufacture and the invention is not to be considered to be limited to any specific cooking liquor, chemicals, cooking process or chemical process combined with mechanical treatment as in the various semichemical production processes. The quantities of chemicals and liquors employed in the foregoing descriptions of the kraft, soda and sulfite pulping processes as well as the corresponding semichemical processes are representative of specific commercial processes and are not to be construed as limiting the present invention. Quantities of chemicals and liquors employed in these processes depend on the types of woods used and the types of pulps being produced as well as processing conditions such as whether batch or continuous processes are employed. Consequently, quantities of the chemicals and liquors which are outside the abovementioned exemplary limits may be employed in these processes. In other words, the present invention resides in the selection and use of the novel treating agents in the various pulping process and this invention is applicable to all pulping processes employed and hence is not to be restricted to the abovementioned examples of pulping processes.

The examples given below are to be considered as being exemplary of the present invention and are not to be regarded as being limiting. The parts and proportions given in the examples are by weight and all temperatures are F. unless otherwise indicated.

EXAMPLE I This example is directed to the use of the condensation product of one mole of phenol and five moles of ethylene oxide as a treating agent for use in formulations of cooking chemicals for the production of wood pulp from wood chips.

The equipment employed in this example consisted of a stainless steel digester having a capacity of about 35 ft. and equipped with facilities for washing and straining the pulp as well as for circulating the liquor during cooking. A total of 200 lbs. of dry wood chips consisting of a mixture of 70% spruce and 30% balsam was charged into the digester. Then 1,100 lbs. of a kraft cooking liquor which contained 44 lbs. of sodium hydroxide, 60 lbs. of sodium sulfide, 1,000 lbs. of water and one-quarter of a pound of the condensation product of one mole of phenol and five moles of ethylene oxide was charged into the digester. The alkalinity of the solution was 22% by weight calculated as Na O and the sulfidity was 30% by weight calculated as Na O. The ratio of liquor to chips in this cook was 5.5 :1. The charge in the digester was brought to an operating temperature of 173 C. and an operating pressure of 100 p.s.i.g. over one hour and held for two hours under these conditions. A control test was made under the same conditions with the exception that the kraft cooking liquor did not contain the treating agent.

Analysis of the two cooks gave the following results:

' The foregoing data show that use of the novel treating agent reduced the potassium permanganate number, reduced the weight of rejects, reduced resin content of the pulp and resulted in an increase in the total yield of pulp.

EXAMPLE H This example demonstrates the advantages of a treating agent which is the condensation product of one mole of phenol and five moles of ethylene oxide over a surfactant which is a commercial treating agent identified as the condensation product of one mole of nonylphenol and nine moles of ethylene oxide.

The equipment employed in this example consisted of a 1 ft. capacity stainless steel laboratory digester having auxiliary equipment for liquor circulation during the cook. Other auxiliary equipment included facilities for screening, washing and drying the pulp.

(A) A total of 3000 g. of dried pine chips was charged into the digester. Then 480 g. of cooking chemicals containing 236 g. of sodium hydroxide, 144 g. of sodium sulfide, 12,000 g. of water and 46 g. of a commercial treating agent which was the condensation product of one mole of nonylphenol and nine moles of ethylene oxide was charged into the digester. The ratio of liquor to chips in the cook was 4:1. The solution of cooking chemicals had an alkalinity of 16% by weight calculated as Na O and a sulfidity of 30% by weight calculated as Na O. The charge of chips and cooking chemicals was heated to 173 F. over forty minutes and digested for two hours at 173 F. A pressure of 110 p.s.i.g. was maintained during the digestion. Analysis showed that the resin content of the pulp was 0.574% (dry fiber weight basis).

(B) The procedure described in part (A) above was repeated with the exception that g. of a treating agent which was the condensation product of one mole of phenol and five moles of ethylene oxide was used instead of 46 g. of the commercial treating agent employed in part (A) above. Analysis showed the resin content of the puly was 0.322% (dry fiber Weight basis). Thus, these data demonstrate that the treating agents of the present invention are considerably more effective than the commercially used nonylphenol ethoxylate. That is, one third as much of the treating agent of the present invention reduces the resin content of the pulp to almost half of the value achieved with the aforesaid treating agent. Further, it was noted that use of the condensation product of one mole of phenol with 5 moles of ethylene oxide instead of the commercially used nonylphenol ethoxylate resulted in a 2.1% increase in total pulp yield over that which had been obtained with the commercially used nonylphenol ethoxylate.

EXAMPLE III A total of 8000 g. of hardwood chips (dry weight) containing approximately 25% by weight of oak chips and approximately 75% by weight of gum chips was charged into a 1 ft. capacity stainless steel laboratory idigester having auxiliary equipment for liquid circulation during the cook. Other auxiliary equipment included facilities for screening, washing and drying the pulp. The Wood dryness content was 51.7% by weight. This cook was a control test, that is, a treating agent was not used. The cook contained 16.0% active alkali based on the percent oven dry weight of the chips and the TAPPI sulfidity was 30.0%. The liquor ratio which included wood moisture was 4.0:1. The maximum cooking temperature was 173 C.; the time for heating the cook from C. to 173 C. was 33 minutes and the cook was held at 173 C. for 100 minutes.

This cook was repeated with a second charge of 80 00 g. of dry chips and differed only from the first cook in that 10 g. by weight of a treating agent which was the condensation product of one mole of phenol with five moles of ethylene oxide was added to the liquor. Addition of the condensation product resulted in a 4.6% increase in the screened yield of pulp and a 2.9% increase in total yield of pulp and further demonstrated the value of this condensation product as a treating agent.

The cook was repeated with a third charge of 8000 g. of dry wood chips and differed only from the first cook in that 10 g. by weight of the condensation product of one mole of phenol with 5 moles of propylene oxide was added to the liquor as a treating agent. Addition of this condensation product resulted in 2.8% increase in the screened yield of pulp as compared to the yield obtained in the first cook which did not contain a treating agent and was a control.

EXAMPLE IV The procedure of Example III was carried out using the treating agents shown in the table below to demonstrate the efiectiveness of these treating agents in reducing the per cent resin content of the pulp (dry fiber basis). These treating agents are condensation products of phenolic compounds and ethylene oxide and are shown as one mole of the particular phenolic compound and the indicated number of moles of ethylene oxide. The percent resin content was determined by extracting 15 g. of pulp (dry fiber weight basis) with a 1:1 benzene-methanol mixture (weight basis) in a Soxhlet extraction apparatus for four hours. The resulting benzene-methanol extract was evaporated to dryness to obtain the resin. The resin was then dried to constant Weight at C. The weight of the dried resin was then employed in the calculation of the percent resin content in the pulp sample (dry fi-ber weight basis). Column 2 of the following table sets forth the percent residual resin content of the pulp after treatment. The effectiveness of the treating agent is determined by the amount of resin remaining in the pulp after treatment. That is, the greater the effectiveness of the treating agent, the smaller will be the amount of resin remaining in the pulp.

7 Table Percent resin content of the Treating agent: pulp (dry fiber weight basis Control (not treating agent) 0.390 One mole of phenol and 1.5 moles of ethylene oxide 0.289 One mole of phenol and 10 moles of ethylene oxide One mole of phenol and moles of ethylene oxide 0.317 One mole of butylphenol and 5 moles of ethylene oxide 0.210

The data in the foregoing table demonstrate the effectiveness of the treating agents in reducing the percent resin content of pulp.

What is claimed is:

1. A process for manufacture of pulp from wood chips which comprises cooking wood chips in a cooking liquor selected from the group consisting of: (a) a kraft cooking liquor, (b) a soda cooking liquor, (c) a sulfite cooking liquor, and (d) combinations of (a), (b) and (c) with mechanical pulping, said liquor containing during said cooking at least about 0.5 pound of at least one treating agent of the formula:

@ooxonn wherein R is selected from the group consisting of hydrogen and an alkyl group containing from one to four carbon atoms, R is selected from the group consisting of hydrogen and an alkyl group containing from one to four carbon atoms with the proviso that the sum of the carbon atoms in R and R does not exceed four carbon atoms, A represents the divalent residue of a vicinal epoxide containing from two to three carbon atoms and n represents an integer of from about 1 to about 30.

2. A process for manufacture of pulp from wood chips which comprises cooking wood chips in a cooking liquor selected from the group consisting of:

(a) a kraft cooking liquor containing from about 150 pounds to about 400 pounds of sodium hydroxide per ton of dry wood chips, from about 50 pounds to about 300 pounds of sodium sulfide per ton of dry wood chips, from about pounds to about 200 pounds of sodium carbonate per ton of dry Wood chips and from about 5,000 pounds to about 12,000 pounds of water per ton of dry wood chips;

(b) a soda cooking liquor containing from about 300 pounds to about 800 pounds of sodium hydroxide per ton of dry wood chips, from about pounds to about 150 pounds of sodium carbonate per ton of dry wood chips and from about 4,000 pounds to about 11,000 pounds of water per ton of dry wood chips; and

(c) a sulfite cooking liquor containing from about 200 pounds to about 500 pounds sulfurous acid per ton of dry wood chips, from about pounds to about 350 pounds of calcium bisulfite per ton of dry wood chips and from about 5,000 pounds to about 11,000 pounds of water per ton of dry wood chips;

said liquor containing during said cooking from about 05 pound to about 10 pounds per ton of dry wood chips, at least one treating agent of the formula:

@Oam

wherein R is selected from the group consisting of hydrogen and an alkyl group containing from one to four carbon atoms, R is selected from the group consisting of hydrogen and an alkyl group containing from one to four carbon atoms with the proviso that the sum of the carbon atoms in R and R does not exceed four carbon atoms, A represents the divalent residue of a vicinal epoxide containing from two to three carbon atoms and n represents an integer of from about 1 to about 3'0.

3. The process of claim 2 wherein said treating agent is References Cited UNITED STATES PATENTS 2,716,058 8/1955 Rapson et al 162-72 2,789,902 4/ 1957 Seymour et al 162-72 3,069,307 12/1962 Boaz et al 162-5 S. LEON BASHORE, Primary Examiner.

US. Cl. X.R. 

